The 507K-X2 is an open reflex sight designed for concealed handgun applications. Features Holosun&&';;s Multiple Reticle System giving the user three reticle options. Shake Awake technology activates the LED at the slightest detection of movement and deactivates the LED during periods of motionless. The 507K-X2 has 10 daytime brightness levels and 2 night-vision compatible levels. 50,000 hours of battery life on setting 6 means you won&&';;t be changing batteries often, but when you do need a replacement, the convenient battery tray allows the user to swap batteries without removing the optic from the slide. This optic is parallax-free and has unlimited eye relief. The Holosun 507K-X2 is IP67 waterpoof rated.